The invention relates to a tightening device for safety belts comprising a cable movable by a drive in a tightening direction and guided about a deflection device, whereby one end of the cable is connected to the drive and the free end is connected to a component of the safety belt. In the area of the deflection device a return lock is provided that is active upon movement of the cable counter to the tightening direction.
Such a tightening device relating to buckle tighteners with the aforementioned features is described in European patent 0 186 880. The cable supporting at one end the belt buckle is guided about a deflection block secured at the vehicle and having a deflection channel for the cable. The other end is connected to the piston of a pyrotechnical drive device since after completion of the tightening movement, loading of the belt buckle in a direction counter to the tightening direction will occur, the pyrotechnical drive device, respectively, its piston is provided with a return lock. This return lock, in a special embodiment of the tightening device known from European patent 01 86 880, has already been moved away from the drive device into the area of deflection, i.e., into the deflection block. For this purpose in the deflection block a chamber is provided for receiving two clamping jaws that surround the cable and upon movement within the chamber will clamp the cable.
The known tightening device has the disadvantage that since the return lock is arranged in the area of the drive device, the parts of the drive device, especially the piston secured at the cable, must be designed for respective loading forces, and inasmuch as the return lock is arranged in the area of the deflection device, the deflection block requires a complicated design including anchoring of the deflection block at the vehicle in order to be able to withstand respective forces.
It is therefore an object of the invention to simplify for a tightening device the deflection device of the cable and the return lock and to simultaneously provide a safely operating return lock for the cable that is easy to install.